Method of drying surfaces and apparatus therefor



Patented Jan. 9, 1940 UNITED STATES PATENT OFFIcE METHOD or name suarscas AND srrAns'rUs mama Frederick J. Groven, Highland Park, men..- assignor to Ford Motor Company, -Dearbom, Mlcln. a corporation of Delaware No Drawing. Application January 23, 1939,

Serial N0. 252.428

4Claims.

within the above-mentioned band, and reflectors" are shown behind each of the radiators whereby 10 the radiating efliciency is increased. However,

it has been found that with all conventional reflectors the longer wave lengths are less efllciently reflected than the shorter wave lengths. Thus, radiation of the required waveband is projected u on the work directly by the radiator but that portion of the radiation which is reflected lays within a wave band shorter than desired.

The object of this invention is to provide a reflector by means of which the longer wave Q length will be reflected with a greater degree of eiilciency than the shorter wave lengths. With my improved reflector radiation of .6 microns is reflected with an efliciency of approximately 85%,- while a radiation of 1.6 microns is reflected with .3 an efllciency of approximately 95%. Thus, a

greater proportion of the longer radiation is reflected. Numerous tests have shown a material reduction in the drying time results with these reflectors, that is, the thermal efliciency of the 30 method is increased.

A further object oi. my invention is to provide a reflector, as above described, which may be periodically cleaned without materially lowering its reflective efllciency. when this apparatus is used as in drying the paint on automobile bodies and the like, the paint is invariably sprayed onto the work.

Particles of the paint float in the air and deposit upon the reflectors. Dust particles that are a vl gth;jzgzggether with the use of reflected radiation of a longer wave length, the reflecting surface being capable of being periodically cleaned" V loss to retain the reflectors at their efllciency. The selection of a suitable reflecting surface might be ascertained by data well known in connection with selective wave radiation reflection. Still, because the reflecting surface must be one which may be readily cleaned, this i limitation would prevent the selection of certain surfaces which otherwise might be thought preferable'.

The following tables illustrate the reflecting eiflciency of silver, gold, copper, aluminum and 10 nickel surfaces for reflecting radiation-within the wave band claimed in the above-mentioned patent:

- I Emo'lelwy in Wave length microns P out SILVER GOLD 1 4 97 1 a 95 (estimate) 1 COPPER ALUMINUM l a 72 1 o 78 1 s so NICKEL From the above table it would normally be expected that a silver surface would be considerably 4 more efllcient than the other surfaces listed. However, silver oxidizes rapidlyso that the initial vw 'efllciency .only lasts for a few hours under the heat and fumes unavoidable in dryin paint. In practice the maximum' working eflciency of a silversurfaceisfullywqt lessthanthat'given' in thctable. Aluminumas' areflectorismuch u less eflicient than silver surfaces but retains its reflecting powers longer. Copper likewise has an original reflecting efliciency of 72% to 95% but oxidizes so rapidly that this condition can only be maintained for a short period. Nickel retains its efilciency longer than either copper, aluminum or silver but has a comparatively low reflecting efficiency being but 65% to 80% so that nickel reflectors get abnormally hot in operation.

A gold surface has a deflecting efllciency of 84% for radiation of .6 micron wave length while the reflecting efliciency is increased to approximately 95% for radiation of 1.6 microns. Con sequently, when the gold reflecting surface is used the reflector stays comparatively cool. An unexpected result from the use of a gold reflecting surface is that the thinners which may con-' dense on the reflector due to its cooler surface may be periodically removed with a weak caustic solution without in anyway impairing the reflecting efficiency of the surface. The result is that a high degree of working emciency is not only initially obtained but is maintained indefinitely. Any other reflecting surface known to the applicant is objectionable either because of its lower efllciency of reflection or because of the inability of the reflector to retain its initial efficiency or because of the inability of the reflector to be cleaned from the condensed products unavoidably deposited thereon. I

My improved method therefore comprises simultaneously drying the surface by the'use of direct radiation having a wave length of .6 to 1.6 microns and with radiation of similar wave length which has been reflected from a gold surface.

In carrying out my improved process I provide conventional paraboloidal shaped reflectors which are plated on their inside surfaces with gold and the gold buffed to a high polish. Standard 250 watt carbon filament lamp bulbs are used within the reflectors. The reflectors are focused on the work so that radiation of from .6 to 1.6 microns is projected directly by the bulbs while radiation averaging slightly longer in wave length is projected upon the work by, the reflectors. The wave length of the combined radiation averages slightly longer than the average of that emitted by the bulbs. After the reflectors have been in use in most installations for three weeks to a month the reflectors are removed and dipped in a weak caustic solution which cleans the gold surfaces of all foreign material. Replating is not required, the reflectors being in'condition for replacement to operate at their original efllciency. Some changes may be made in the method of carrying out my improved process without departing from the spirit of my invention and it is my intention to cover by my claims such changes as may reasonably be included within the scope thereof.

I claim as my invention:

1. A method of drying surfaces comprising, exposing the material to be dried to radiation of a wave length between .6 and 1.6 microns which is projected thereon. directly from a radi ting source, and simultaneously exposing said material to radiation from said source whic has been reflected from a gold surface. v

2. The method of drying point comprising, exposing a wet painted surface to radiation of a wave length between .6 and 1.6 microns which is projected thereon directly from a radiating source, and simultaneously exposing said surface to radiation from said source which has been reflected from -a gold surface.

3. The method of drying paint comprising, exposing a wet-painted surface to radiation, the major portion of which is of a wave length between 1.6 and .6 microns, and simultaneously exposing said surface to reflected radiation which averages slightly longer in wave length, said re flected radiation being obtained from a gold surface.

4. An apparatus for drying surfaces comprising, a radiating source emitting radiation uni-- formly. in substantially all directions disposed adjacent to said'surface, the major portion of which radiation is of a wave length between 1.6 and .6 microns, and a gold reflecting surface disposed behind said source which reflects a portion of said radiation upon the surface to be dried. FREDERICK J. GROVEN.

CERTIFICATE OF CORRECTION- L/ Patent "Ne; 2,;86,067. I January 9; 191 0.

It is hereby certified that errox appears in the above numbered patent reqniring correctio'xfiae follcwvs: In the grant, line 1, and in 'the headingand signature to the orinted specification, name of inventor, for'"Freder1ck-j J Groven" reed-- Fr'edrick J, Groven; page 2, firet column, line 10,- for "deflecting" read reflecting; sec-0nd coiumn, line 2h', c1aim 2, for the ford "point" read peinfyand thet the 'eaid Letters Patent shonld be read with thiecorrection therein that the same may conform to the record er the case in f lPai ienii 0rf1ce.-- Q

signed and'ineaji'lled' this 9thf-day of April, A. D. l91 10} f I Henry V'an Arsdal-e; (.Sal)-" Acting Congnis'sioneroi' Pa tent.

- CERTIFICATE OF C(JRRECTION'. L/ Patent'No." 2,186,067. January 9', I9L;0.

v It is hereby certified that erroffippears in the above numbered patentreqfiiring borrectio'rt'as; follows: In th s grant, ling l, and in "the headingand sigrgatur-Qg to the pz 'iptd speification, name of inventor, for' "Frederick J .1 Graven"- ra dE- Fredrick J, Groverl; page 2, first column, lin 10;; for 1 "deflecting" re'acl' reflecting; sec-0nd Column, 1ine -2h', c1ai,m 2, for the wbrd ""p o1 n1;" rea'd painis'ynd that the 'gaid Latte 17s Patent should be read with thiscorrection there in tha t th same may conform td the record 61 the case in t hmrat nfi orr1'ce.-

Signed and'ineafiigd lthis 9'thf-day of-April, A. D. 19L1on 

